Recent activity in various fields of research such as in controlled thermonuclear fusion, generating plasmas to produce X-rays, and shock treatment of materials requires increasingly more powerful lasers to provide the extremely high power densities that are required for optimum results.
Such uses of high powered lasers are disclosed and claimed in the following United States patent applications and patents of Philip J. Mallozzi et al., Ser. No. 265,799 filed June 23, 1972, for Altering Material Properties, now U.S. Pat. No. 3,850,698, issued Nov. 26, 1974; Ser. No. 319,756, filed Dec. 29, 1972, for Producing X-Rays, and Ser. No. 353,691 filed Apr. 23, 1973, (now replaced by a continuation thereof, Ser. No. 650,803, filed Jan. 20, 1976) for Applying Radiation.
High powered lasers typically comprise several stages of amplification with serveral amplifiers operating in parallel in the final stage. However, the power that can be passed through many optical devices such as amplifiers made of glass is limited because excessive power density damages the material. In some arrangements, even where apparatus may not be damaged, the shape or other characteristics of a radiation pulse may be adversely affected by the presence of more than a given power density in a region.
The effects of such limitations are substantially reduced by the present invention, which enables an amplifier to pass an effective total power density that may be approximately doubles, triple, or even a higher multiple of the highest power density it is capable of passing when used in conventional ways. Thus by means of the present invention the size, complexity, and cost of providing a very powerful laser facility have been kept well below what otherwise would have been required to provide the same power.